Key

(from Allan Hancock Pacific expeditions vol. 2 1935-1940)

Order Palaeonemertea

Key to the Families Represented on Pacific Coast

1. Mouth situated immediately behind brain ; nephridia with single pair of large collecting tubules and efferent ducts.... 2

2. Lateral nerves situated at base of body epithelium or external to circular muscles of body walls, at least in anterior portion of body; internal circular musculature relatively thin; lateral sense organs present ; rhynchocoel vessels absent....Tubulanidae
2. Lateral nerves situated outside muscular layers in anterior portion of esophageal region but imbedded in longitudinal muscles in nephridial region and posteriorly; internal circular musculature enormously developed in nephridial region; lateral sense organs absent; rhynchocoel vessels present....Carinomidae

1. Mouth situated far behind brain ; nephridia with very numerous minute efferent ducts; body filiform; head sharply pointed....Cephalotrichidae